Methyl iodide → 3,5-Dibromo-4-methylpyridine

Temperature

-10 °C

A solution of n-butyllithium in hexane (1.6 N, 16 ml) is added dropwise, under argon, to a solution of diisopropylamine (3.6 ml, 1.02 equiv.) in anhydrous THF (145 ml) maintained at −10° C. The reaction mixture is cooled to −78° C. and then a solution of 3,5-dibromopyridine (5.92 g, 25 mmol) in THF (200 ml), cooled to −78° C., is added dropwise. The reaction mixture is stirred for 30 min and then methyl iodide (2.17 ml, 1.4 equiv.) is added dropwise. The stirring is maintained for 2 h at −78° C. A saturated aqueous NH4Cl solution (120 ml) is added. After evaporation of the solvents, the reaction mixture is extracted with EtOAc. The organic phase is washed with brine, dried over MgSO4 and evaporated. The yellow solid obtained is taken up with EtOAc. The suspension is filtered. The filtrate is evaporated and the residue is chromatographed on silica gel, elution being carried out with a petroleum ether/EtOAc (97.5/2.5) mixture. 1.67 g of product are obtained in the form of a white solid.

1. temperatureThe reaction mixture is cooled to −78° C.
2. additionis added dropwise
3. temperatureThe stirring is maintained for 2 h at −78° C
4. customAfter evaporation of the solvents
5. extractionthe reaction mixture is extracted with EtOAc
6. washThe organic phase is washed with brine
7. dry with materialdried over MgSO4
8. customevaporated
9. customThe yellow solid obtained
10. filtrationThe suspension is filtered
11. customThe filtrate is evaporated
12. customthe residue is chromatographed on silica gel, elution

ORD record

ord-db6d9442e6e546dbbc1c8fbf5834fc96

Source dataset

uspto-grants-2010_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07842711B2